Observation of high voltage resonances in one-dimensional arrays

Dynamic states in parallel one-dimensional arrays of small Josephson tunnel junctions are experimentally investigated in the presence of an external magnetic field H. In addition to conventional Fiske modes and flux-flow branches, the current-voltage characteristics exhibit a new type of resonances which appear in higher voltage regions as additional groups of resonant steps. These resonances can be explained in terms of a simple kinematic model, in the limit where the fluxon frequency is higher than the maximum linear wave frequency. The model is in good agreement with reported experiments.